Touching cloth and can't hold it in? Make sure this app is the first thing to run.
Toilet Finder, from developer BeTomorrow - no, not Pee Tomorrow - uses the GPS co-ordinates of your iPhone or Android device to generate a map of public conveniences in the vicinity.
Toilet Finder App Bum steer: Toilet Finder locates lavs
The …

Does she

Pan and zoom

Just tried it

and I'm not impressed. This was on an Android phone. First, it insists on having GPS on, which is going to eat the battery, even though a coarse position from cell bases would probably be sufficient. Second, the list of loos near my home seemed impressively accurate, but when I asked for them to be displayed on the map the positions shown were bizarre. The nearest, which is about 500m west of me was shown as about 500 m east, down an obscure side road. Parents with small kids are not going to be happy about getting a mystery tour of a local housing estate rather than a loo.

Find Toilets

As a keen OpenStreetMap supporter I've been using the alternative Find Toilets app for a while now. It's not quite as complete as Toilet Finder yet, but the fact that my submissions get added to OSM rather than locking it in some developers database, makes it better in my opinion. Find Toilets is definitely available in the UK app store (cos that's where I got it from).